An illumination apparatus, for example a spotlight used for illuminating an article on display, may use an LED (light emitting diode) as a light source. An LED illumination apparatus includes a substrate on which a plurality of LEDs are mounted, a plurality of lenses which project light from the individual LEDs, and a lamp body having a main body which accommodates the substrate and the lenses.
The substrate is made of metal higher in thermal conductivity. An insulating layer is formed on the front face of the substrate, a wiring layer patterned in a predetermined manner is formed on the insulating layer, and a plurality of LEDs are mounted on the wiring layer. The rear face of the substrate is attached to a radiator of the main body so that heat generated by the LEDs on lighting can be conducted from the substrate to the radiator and released from the radiator.
In order to efficiently conduct the heat from the substrate to the radiator, the substrate is fastened and fixed to the radiator with a screw, by which the substrate is firmly attached to the radiator. The shank of the screw penetrates through the substrate from the front face of the substrate and is screwed into the radiator, and the head of the screw is joined to the front face of the substrate.
However, although current-carrying parts such as the wiring layer and the plurality of LEDs are arranged on the front face of the substrate, it is necessary to provide a clearance greater than a predetermined insulation distance between the current-carrying parts and the screw.
In a conventional illumination apparatus, since the head of a screw is directly joined to a substrate, it is necessary to secure an insulation distance from the current-carrying parts on the basis of an outermost diameter portion of the head of the screw. Therefore, for example, where the screw is arranged between a plurality of LEDs mounted on the substrate, the screw is arranged such that the LEDs are spaced away from each other so as to give a clearance greater than a predetermined insulation distance from the outermost diameter portion of the head of the screw. Thus, the substrate is large and the illumination apparatus is increased in size accordingly.
An object of the present invention is to provide an illumination apparatus which can be downsized.